Ductal carcinomas in situ (DCIS) accounts for about 20% of newly diagnosed breast cancers in the United States amounting to nearly 40,000 cases per year. DCIS is characterized by marked pathologic and clinical heterogeneity. Only a minority of DCIS have the capacity to progress to stromally invasive tumors. From 30-50% of high grade (HG) DCIS lesions progress to invasive carcinoma. In contrast, only about 10-20% of low grade (LG) DCIS progress to an invasive carcinoma. Standard pathologic evaluation does not distinguish DCIS lesions with or without the capacity to progress. In addition, no molecular changes have been identified that reliably differentiate indolent from aggressive DCIS.
As there are no distinguishing features of indolent DCIS, the great majority of patients tend to be over-treated. Patients with a diagnosis of DCIS receive additional surgery, radiation or systemic therapy. Such aggressive treatments are not necessary in 80-90% of LG DCIS and in 50-70% of HG DCIS cases.